Ground Granulated Blast Furnace Slag (GGBS) is widely used in concrete mixes primarily to enhance its performance and longevity.
Adding GGBS to concrete significantly improves its properties, making it a preferred choice for various construction projects. The core reasons for using GGBS relate directly to the enhanced qualities it imparts to the concrete.
Key Benefits of Using GGBS in Concrete
Based on expert information, Ground Granulated Blast Furnace Slag (GGBS) offers great durability, reducing the likelihood of concrete thermal cracking, and it improves concrete's resistance to damage from alkali-silica reaction, sulphates and chlorides. These benefits contribute to more robust and longer-lasting concrete structures.
Here's a breakdown of the main advantages:
- Enhanced Durability: GGBS concrete develops a denser microstructure over time compared to traditional concrete. This reduced permeability makes the concrete matrix more resistant to the ingress of aggressive substances.
- Reduced Thermal Cracking: GGBS concrete generates less heat during the hydration process (the chemical reaction between cement and water) compared to ordinary Portland cement. This lower heat evolution minimizes thermal stresses, significantly reducing the risk of cracking, especially in large concrete pours.
- Improved Resistance to Deleterious Reactions: GGBS actively combats common causes of concrete deterioration:
- Alkali-Silica Reaction (ASR): By consuming the alkali hydroxides in the pore water and altering the pore solution chemistry, GGBS effectively suppresses ASR, preventing the expansive and cracking effects of this reaction.
- Sulphate Attack: GGBS reduces the amount of calcium hydroxide (CH) in the concrete, which is vulnerable to sulphate attack. It also refines the pore structure, hindering sulphate penetration. This makes concrete more suitable for environments exposed to sulphates, such as marine or industrial settings.
- Chloride Ingress: The denser structure and reduced permeability provided by GGBS make it much harder for chloride ions to penetrate the concrete. This is crucial for preventing the corrosion of steel reinforcement within the concrete, particularly vital in coastal areas or structures exposed to de-icing salts.
Summary of GGBS Advantages
| Benefit | Impact on Concrete |
|---|---|
| Great Durability | Longer service life, reduced permeability |
| Reduced Thermal Cracking | Minimized stresses from heat of hydration |
| Resistance to Alkali-Silica Reaction | Prevents internal expansion and cracking |
| Resistance to Sulphates | Protects against chemical attack from sulphates |
| Resistance to Chlorides | Prevents steel reinforcement corrosion |
Incorporating GGBS into concrete mixes is a strategic choice for enhancing performance, increasing lifespan, and improving resistance to environmental stressors, leading to more sustainable and resilient construction.
